For the Chicken and Beans
For the lemon–rosemary oil:
Heat the oven and season the chicken. Adjust an oven rack to the lower-middle position and preheat the oven to 325°F (160°C). For a countertop oven, use the lower rack, with adequate clearance above the pan. Pat the chicken dry and season on both sides with salt, pepper, and a little MSG, if using.
Brown the chicken. Heat the olive oil in a wide, oven-safe braiser or deep sauté pan over medium-high heat until shimmering. Add the chicken skin-side down in a single layer. Cook, adjusting the heat as necessary, until the skin is deep golden brown and some of its fat has rendered, about 8 to 12 minutes. Flip and cook until lightly browned on the second side, about 1 to 2 minutes. Transfer to a plate, skin-side up, leaving the rendered fat in the pan. If there is an unusually large amount of fat, spoon off the excess, leaving about 2 tablespoons.
Sweat the vegetables. Reduce the heat to medium. Add the onion, carrot, celery, and rosemary sprigs. Cook, stirring frequently, until the vegetables have softened without taking on much color, about 5 to 7 minutes. Add the garlic and cook, stirring, until fragrant, about 30 seconds.
Build the braise. Add the spinach and cook, stirring, until wilted. Add the beans with their liquid and enough stock to make a brothy stew, scraping up any browned bits from the bottom of the pan. Bring to a simmer. Taste and season lightly with salt and pepper, leaving the liquid slightly less salty than you want the finished dish.
Add the chicken and braise. Return the chicken and any accumulated juices to the pan. Nestle the thighs into the beans skin-side up, keeping their skin above the liquid. Add a little more stock if needed, or spoon some liquid out if it covers the skin. Transfer to the oven and cook uncovered until the chicken is very tender and the skin is crisp, about 45 minutes. Check the pan during cooking; if the beans begin to dry out, add a little stock or water around the chicken.
Make the finishing oil. Meanwhile, while the chicken rests briefly, stir together the minced rosemary, lemon zest, lemon juice, and olive oil in a small bowl. Season to taste with salt, pepper, and MSG, if using.
Finish and serve. Remove the three rosemary stems from the beans (or leave them in and let your guests pick them out themselves, the lazy ingrates). Taste the broth and adjust the seasoning. Drizzle the lemon–rosemary oil over the beans and around the chicken. Serve in shallow bowls with the chicken skin-side up on top of the beans and spinach. Add another drizzle of good olive oil if you like.
